Non-electric detonator

ABSTRACT

A detonator ( 10 ) has a constant-diameter shell ( 12 ) which has a significantly higher shell length-to-diameter (outside diameter) ratio than prior art detonators. The shell ( 12 ) is configured to hold an explosive output charge ( 18 ) which is cylindrical in configuration and has a charge L:D ratio which is greater than that of prior art constant diameter detonators. As a result, a significant portion of the output signal of the detonator is directed laterally and it is feasible to transfer signals to a plurality of receptor lines disposed along that portion of the length of the detonator which is co-extensive with the length of the explosive output charge ( 18 ). A connector block ( 26 ) is configured to hold at least one array of receptor lines in side-by-side arrangement along the side of the detonator ( 10 ), and transversely to the longitudinal axis of the detonator ( 10 ).

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to detonators and, in particular,to non-electric detonators employed for transmitting initiation signalsto receptor lines and to explosive charges.

[0003] 2. Related Art

[0004] Detonators are commonly used not only to initiate explosivecharges, e.g., booster charges, but also to initiate non-electric,impulse signals in signal lines such as low-energy detonating cords,shock tubes and low velocity signal tubes (“deflagration tubes”) thatcarry the impulse signal to other devices. Conventional non-electricdetonators comprise an output charge of explosive material packed in theclosed end of a cylindrical shell, the other end of the shell having aninput signal line connected thereto. Conventionally, the shell iscrimped onto a bushing surrounding the signal line in the crimp region,to help secure the shell to the line and to close the open end of theshell in order to seal the interior of the shell against theenvironment. Some detonators include a pyrotechnic or electronic delayelement between the output charge and the signal line to interpose adelay between the receipt of the initiation signal in the detonator andthe release of the output signal by detonation of the output charge ofthe detonator. Upon receipt of an initiation signal from the signalline, the detonator is initiated and its output charge generates anexplosive output signal that can be used to initiate signals in one ormore receptor lines or to detonate an explosive charge. Numerousdevices, commonly referred to as “connector blocks”, are known in theart for holding receptor lines in signal-receiving relation to theexplosive end of the detonator.

[0005] The explosive output charge in a detonator conforms to theinterior of the detonator shell in which it is disposed and, inasmuch asthe conventional detonator shell has a circular cross section, so toodoes the output charge. Accordingly, the explosive output charge willhave a diameter defined by the interior diameter of the detonator shell.The length of the output charge refers to its depth in the shell. Inprior art low-output detonators, the ratio of the length of theexplosive charge to its diameter, sometimes below referred to as “thecharge L:D ratio”, is typically less than 1, and is commonly about 0.5:1or less, resulting in a disc-like configuration. For example, a typicalprior art detonator will have an outside diameter of about 0.28 to 0.295inch (about 7.11 to 7.49 mm) and an inside diameter of about 0.26 inch(about 6.60 mm), resulting in the output charge having the samediameter, D, of about 0.26 inch (about 6.60 mm). The typical prior artoutput charge has a length L (measured along the longitudinal axis ofthe detonator) of about 0.1 inch (about 2.54 mm), resulting in a chargeL:D ratio of about 0.38:1.

[0006] As a result of the disc-like configuration of the prior artexplosive output charge, the output signal of a prior art detonator isstrongest at the explosive tip at the axial end of the detonator andaround the circumference of the detonator in the lateral regionimmediately adjacent the explosive tip. The effective lateral outputregion of a prior art detonator typically does not exceed a distancealong the longitudinal axis of the detonator which is equal to thediameter of one usual-sized receptor line, e.g., shock tube or alow-energy detonating cord. Accordingly, most prior art connector blocksare configured to hold receptor lines only against the explosive tip ofthe detonator and at opposite sides of the detonator, immediatelyadjacent the explosive tip.

[0007] An exception to such placement of the receptor lines is shown inU.S. Pat. No. 6,349,648, issued to J. Capers et al on Feb. 26, 2002,which is a division of U.S. Pat. No. 6,305,287, issued to J. Capers etal on Oct. 23, 2001. The '648 Patent, like the '287 Patent, discloses adetonator and a connector block for holding the same in contact with aplurality of receptor lines. As best seen in FIGS. 1E, 2, 3 and 5, andas described starting at column 3, line 54, the detonator B is formedfrom a generally cylindrical metallic shell of circular cross-section,preferably formed from aluminum about 0.5 mm thick and shaped as shownin FIG. 5. Detonator B is comprised of a main cylindrical section 10, asmaller-diameter cylindrical explosive end portion 12, and a transitionportion 14. The shell of detonator B is said to preferably beaxisymmetric with respect to its longitudinal axis 15 (FIG. 5). The main(output) explosive charge of detonator B is located in explosive endportion 12 (FIGS. 6 and 7), and is distributed along the axial length ofend portion 12 so as to initiate shock tubes D (FIG. 1B). The explosiveforce of the ignited main charge will ignite the shock tubes D held inplace alongside the length of end portion 12. An initiating shock tube16 is connected to the opposite signal end 18 of detonator B, as bestseen in FIGS. 1E, 2 and 3.

[0008] The connector block, referred to as “block body A”, is describedstarting at column 4, line 20 and is configured to hold a plurality ofshock tubes D orthogonally to explosive end portion 12. As illustratedin FIGS. 6 and 7, and described at column 5, line 61 to column 6, line62, various loadings of explosives such as PETN and dextrinated leadazide may be loaded within end portion 12. FIG. 6 shows theinterposition of a small, fast-burning pyrotechnic charge 64, e.g., azirconium/red lead mixture, placed on top of the main lead azide chargein order to “protect against explosion of the charges during subsequentloading operations.” (Column 6, lines 13-17.) FIG. 7 shows an embodimentin which the PETN charge is filled to above the transition point betweenthe small-diameter explosive end portion 12 and main cylindrical section10. These expedients show attempts to deal with the difficultiesinherent in loading the explosive and pyrotechnic components into theend of a detonator which transitions from a large diameter to a smallerdiameter end portion.

SUMMARY OF THE INVENTION

[0009] In accordance with the present invention there is provided anon-electric detonator comprising the following components. Acylindrical shell defines a shell interior, the shell having asubstantially constant outside diameter not greater than about 6 mm,e.g., about 3.3 to about 5.5 mm, a closed end and an opposite, open end.An explosive output charge is contained within the shell at the closedend thereof, the explosive output charge being in the shape of acylindrical column and having a charge L:D ratio of from about 3 toabout 20, or about 24, e.g., from about 4 to about 10, or from about 4to about 12. A non-electric input signal transmission line is receivedand sealed within the open end of the shell and disposed insignal-transfer relationship with the explosive charge.

[0010] Another aspect of the present invention provides a non-electricdetonator comprising the following components. A cylindrical shelldefines a shell interior and has a length as defined below, the shellbeing of substantially constant outside diameter not greater than about6 mm, and having a closed end and an opposite, open end. An explosiveoutput charge is contained within the shell at the closed end thereofand a non-electric input signal transmission line is received and sealedwithin the open end of the shell and disposed in signal-transferrelationship with the explosive charge. The length of the shell is suchthat the ratio of its length to its diameter is from about 8 to about23, e.g., from about 12 to about 20. For example, the length of theshell may be from about 25 to about 79 mm.

[0011] Various aspects of the present invention may provide one or moreof the following features, alone or in combinations of two or morethereof. The explosive output charge may be in the shape of acylindrical column having a charge length-to-diameter ratio of fromabout 4 to about 10; the explosive output charge may be in the shape ofa cylindrical column having a length of from about 20 to about 26 mm;the explosive output charge may have a diameter of from about 2.5 toabout 5 mm; the input signal transmission line may comprise shock tube;a delay train may be interposed between, and in signal-transferrelationship with, the explosive output charge and the input signaltransmission line; the explosive output charge may contain an inertdiluent; the explosive output charge may be in the shape of acylindrical column and an attenuation sleeve may be disposed about atleast a portion of the length of the explosive charge, with theattenuation sleeve being disposed either within the shell or on theexterior of the shell; the attenuation sleeve may extend over the entirelength of the explosive charge; the input-signal transmission line mayhave an outside diameter which is substantially the same as the insidediameter of the shell; the detonator may further comprise a sealantdisposed between the input signal transmission line and the inside wallof the shell and disposed to seal the shell interior from theenvironment.

[0012] Another aspect of the present invention provides a non-electricdetonator comprising the following components. A cylindrical shelldefines a shell interior and has a closed end and an opposite, open end,the shell being of substantially constant outside diameter not greaterthan about 6 mm, and of substantially constant inside diameter. Anexplosive output charge is contained within the shell at the closed endthereof, the explosive output charge having the shape of a cylindricalcolumn having a length of from about 20 to about 26 mm and a diameter offrom about 2.5 to about 5 mm. A non-electric input signal transmissionline is received and sealed within the open end of the shell andterminates in an end disposed within the shell in signal-transferrelationship with the explosive charge.

[0013] In a related aspect of the present invention, a delay train maybe interposed between, and in signal-transfer relationship with, theexplosive charge and the input signal transmission line.

[0014] Other aspects of the present invention will become apparent fromthe following description.

[0015] Reference herein and in the claims to “constant diameter” or“substantially constant diameter” of the detonator shell means that theoutside diameter of the shell is substantially the same along the entirelength of the shell, from the closed to the open end thereof Thedefinition therefore distinguishes over prior art detonators of the typeillustrated in FIG. 1 and described below. The defined terms do notexclude detonator shells containing crimps or other such minordeformations, such as a slight taper to facilitate manufacturingoperations.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]FIG. 1 is a side elevation view of a detonator in accordance withthe prior art;

[0017]FIGS. 2 and 3 are schematic, cross-sectional side elevation viewsof (the same) detonator in accordance with a first embodiment of thepresent invention, FIG. 3 showing one array of signal receptor linespositioned in contact with the detonator;

[0018]FIG. 2A is a view, enlarged relative to FIG. 2, of the portion ofFIG. 2 enclosed by the circle A;

[0019]FIG. 3A is a cross-sectional view taken along line I-I of FIG. 3;

[0020]FIG. 4 is a schematic, cross-sectional side elevation view of adetonator in accordance with a second embodiment of the presentinvention, and showing two arrays of signal receptor lines positioned incontact with the detonator;

[0021]FIG. 5 is a top view of a connector block adapted to secure eitherone or two arrays of signal receptor lines in contact with a detonatorin accordance with the present invention;

[0022]FIG. 5A is a cross-sectional side elevation view taken along lineII-II of FIG. 5;

[0023]FIG. 6 is a schematic, cross-sectional side elevation view ofdetonator 10 of FIGS. 2 and 3 which, in accordance with a thirdembodiment of the present invention, has a short external attenuationsleeve attached thereto;

[0024]FIG. 7 is a schematic, cross-sectional side elevation view of adetonator in accordance with a fourth embodiment of the presentinvention;

[0025]FIG. 8 is a schematic, cross-sectional side elevation view of adetonator in accordance with a fifth embodiment of the presentinvention;

[0026]FIG. 9 is a schematic, cross-sectional side elevation view of adetonator in accordance with a sixth embodiment of the presentinvention; and

[0027]FIG. 10 is a schematic, cross-sectional side elevation view ofdetonator 410 of FIG. 9 which, in accordance with a seventh embodimentof the present invention, has a long external attenuation sleeveattached thereto.

DETAILED DESCRIPTION OF THE INVENTION

[0028] The present invention provides a detonator comprising a hollowshell closed at one end and open at the other and having a constantdiameter which is significantly smaller than that of prior art constantdiameter detonators. (Unless otherwise stated, all references herein andin the claims to the shell length-to-diameter ratio are to the outsidediameter of the shell. As a result, the detonators of the presentinvention have a length-to-diameter ratio considerably higher than thatof prior art detonators. The length of the detonators of the presentinvention is generally comparable to, and may be the same as, those ofprior art detonators. The resulting “thin” detonators of the presentinvention thus have a configuration which inspires reference to them as“pencil” detonators. The explosive output charge contained at the closedend of such “pencil” detonators is necessarily configured to fit withinthe shell and, consequently, the explosive output charge has a highcharge L:D ratio, i.e., the ratio of the length of the charge to itsdiameter. The diameter of the charge is, of course, limited by theinside diameter of the shell. The fact that the explosive output chargeis contained within a shell of constant diameter obviates difficulties(discussed below) which are inherent in detonators which have a largeand a small diameter section connected by a transition section, with theexplosive output charge contained within the small diameter section.

[0029] Referring now to FIG. 1, there is shown a prior art detonator 1comprised of a cylindrical metal shell having a cylindrical main section2 and a smaller-diameter cylindrical end portion 3 which terminates in aclosed end 4 and within which is contained the explosive output charge(not shown). A shock tube 5 enters the open end of the cylindrical mainsection 2 and extends therein in signal-transfer relation with apyrotechnic delay train (not shown) contained within cylindrical mainsection 2. A transition portion 6 of the shell connects cylindrical mainsection 2 and cylindrical end portion 3. A crimp 7 at the open end 8 ofcylindrical main section 2 secures a bushing 9 about shock tube 5 inorder to seal the interior of the shell of detonator 1 against theenvironment. As described in detail in the above-mentioned U.S. Pat.Nos. 6,305,287 and 6,349,648, if the cylindrical end portion 3 isunderfilled with the explosive outlet charge, a gap may result betweenthe pyrotechnic delay train (or the end of the shock tube within theshell), which would decrease reliability of the detonator 1, as it mightfail to fire because of the gap. An underfill situation would exist ifthe explosive output charge extended within cylindrical end portion 3from closed end 4 thereof only to underfill line U-U. If an overfillsituation exists, i.e., if the explosive output charge extends fromclosed end 4 to overfill line O-O, upon seating the pyrotechnic delaytrain or other components within cylindrical main section 2, theoverflow explosive may be pinched between the decreasing diameter oftransition portion 6 and the inserted pyrotechnic delay train or othercomponent, thereby risking detonation of the explosive output chargeduring the assembly operation. Because the explosive output chargewithin cylindrical end portion 3 immediately adjacent transition portion6 may be a particularly sensitive explosive, such as lead azide,overfilling presents a significant risk of detonation during assembly.

[0030] A detonator 10 in accordance with one embodiment of the presentinvention is shown in FIGS. 2 and 3 and comprises an elongatecylindrical shell 12 of substantially constant outside diameter OD andsubstantially constant inside diameter ID. Shell 12 is of circular crosssection and has a closed end 12 a and an opposite, open end 12 b. Openend 12 b is secured at crimp 12 c to an initiation signal line which, inthe illustrated embodiment, comprises a shock tube 14. Shock tube 14terminates within shell 12 at end 14 a thereof and abuts an isolationmember 16 which provides a stand-off between the end 14 a of shock tube14 and the reactive materials in shell 12. As is well known, isolationmember 16 also serves to inhibit the transfer of static electricity fromshock tube 14 to the reactive or explosive materials within shell 12.

[0031] In the illustrated embodiment, a pyrotechnic delay train member20 is interposed between isolation member 16 and explosive output charge18. Charge 18 comprises a top or primary charge 18 a and a base charge18 b. Primary charge 18 a typically comprises a small quantity of aprimary explosive material (e.g., lead azide, diazodinitrophenol,hexanitromannite, lead styphnate, etc.) that is sensitive to the signalit receives from pyrotechnic delay train member 20, which signal wasgenerated by the signal emitted from end 14 a of shock tube 14. As iswell known in the art, shock tube 14 may be initiated by any suitablemeans, such as a spark generated at the end of shock tube 14 oppositefrom end 14 a, or by a detonator or low-energy detonating cord utilizedto initiate the signal in shock tube 14 from externally thereof. As iswell known, pyrotechnic delay train member 20 is of a selectedcomposition and length to provide a desired predetermined time lapsebetween emission of the signal from end 14 a of shock tube 14 andinitiation of explosive output charge 18. Delay train member 20typically comprises a metal tube (lead, pewter or other suitable metal)having a core of compressed pyrotechnic material, or a pressed powdercharge, as is well known in the art.

[0032] Base charge 18 b typically comprises one or more secondaryexplosive materials (e.g., PETN, RDX, HMX, etc.). The cushion disc andbuffer commonly employed in prior art detonators may be omitted orincluded as desired. Such components are well known in the art and arenot illustrated or described in detail herein. When initiated by shocktube 14, primary charge 18 a releases sufficient energy to initiate basecharge 18 b. The primary charge 18 a may be omitted if the base charge18 b is sufficiently sensitive to the signal initiated by shock tube 14.Such a base charge may comprise one or more primary explosive materialsor a combination of primary and secondary explosive materials.

[0033] Detonator 10 differs from prior art detonators in the highlength-to-diameter ratio of shell 12 and the consequent high charge L:Dratio of explosive output charge 18. The charge L:D ratio of explosiveoutput charge 18 may vary from about 4 to about 10. Usually, shell 12 isof circular cross section, so that the explosive output charge 18 is inthe form of a column of circular cross section.

[0034] The overall length of shell 12 measured along the longitudinalaxis thereof from closed end 12 a to open end 12 b is limited by twoconsiderations. Because most detonator shells 12 are formed fromaluminum by a drawing process, the maximum obtainable length is slightlymore than 3 inches (76.2 mm), about 3.1 inches (78.7 mm). Detonatorshell 12 may be made shorter, but generally will not exceed about 3.1inches (78.7 mm) in length. Lengths B and C (FIG. 3) are measured alongthe longitudinal axis of detonator 10. Length B is the length of theexplosive output charge 18 and may be from about 0.4 to about 1 inch(about 10 to 26 mm), e.g., about 0.8 to 1 inch (20 to 26 mm). Length Cis the length of the pyrotechnic delay train member 20.

[0035] The inside diameter ID of detonator shell 12, and consequentlythe maximum diameter of explosive output charge 18, may vary from about0.1 to about 0.196 inch (2.5 to 5 mm). For example, the inside diameterID may vary from about 0.110 inch (2.8 mm) to about 0.150 inch (3.81mm). The outside diameter OD of shell 12 may vary from about 0.130 inch(3.3 mm) to about 0.236 inch (6.0 mm), e.g., from about 0.132 inch (3.35mm) to about 0.150 inch (3.81 mm). Usually, the thickness of thelongitudinal wall of shell 12 is substantially uniform, so that bothinside diameter ID and outside diameter OD are substantially constant.

[0036] By thus reducing the diameter and extending the length ofexplosive output charge 18 as compared to the explosive output charge ofprior art constant diameter detonators, a significant degree of lateralexplosive force is attained along the entire length B of charge 18. Atthe dimensions illustrated, and utilizing a conventional explosive suchas PETN as explosive output charge 18, the lateral explosive force iscomparable to that of detonating cord having a PETN core load of 33grains per linear foot (108.3 grains per meter). This is a verysignificant explosive force which is capable of initiating a pluralityof shock tubes or other receptor lines placed along the side of thedetonator along the length B thereof as illustrated, for example, inFIGS. 3 and 4. In fact, the resultant explosive force has been found tobe sufficiently great that in some surface applications, it isexcessive. As is well known in the art, in large blasting operations, alarge number of surface connectors comprising connector blocks (asdescribed below) containing detonators are disposed throughout theblasting area to transfer signals to receptor lines attached thereto. Itis desired to reduce the noise and shrapnel engendered by the detonationof, often, many hundreds of such detonators. Reduction of shrapnel isimportant (a connector block as described below aids in this effort)because shrapnel may sever a connecting line before the explosive signalhas passed through it, thereby interrupting the desired sequence ofexplosions. In accordance with practices of the present invention, itmay therefore be necessary or desirable to attenuate the explosive forceof the detonator for use in some surface applications. Severalexpedients for doing so are described below.

[0037] The inside diameter of shell 12 of detonator 10 may be selectedto be identical or only very slightly larger than the outside diameterof the non-electric input signal transmission line which is received andsealed within the open end of shell 12. In the case of shock tube, astandard shock tube commercially available has an outside diameter ofabout 0.118 inch (3.00 mm) and commercially available mini shock tubehas an outside diameter of about 0.085 inch (2.16 mm). By selecting aninside diameter ID of shell 12 which approximately corresponds to theoutside diameter of the non-electric input signal transmission line,e.g., shock tube 14 of FIG. 2, the separate bushing required to closethe open end 12 b of shell 12 may be eliminated. The ID of shell 12 maythus be about 0.118 inch (3.00 mm) or slightly larger, to accommodate astandard size shock tube, or even as small as about 0.085 inch (2.16 mm)to accommodate mini shock tube. The latter size may, however, presentproblems in emplacing other components within the shell 12. In theembodiment illustrated in FIGS. 2 and 3, crimp 12 c is formed in shell12 to directly engage shock tube 14 to seal the interior of shell 12from the environment. As best seen in FIG. 2A, a suitable sealant 22 maybe applied between the exterior of shock tube 14 and the interior ofshell 12 in the vicinity of crimp 12 c to improve the effectiveness ofthe seal. Sealant 22 may be any suitable material such a curableadhesive or sealant or the like.

[0038] Aside from the relative dimensions of the length and diameter ofshell 12 and of explosive output charge 18, and the resulting enhancedrange of lateral explosive output, the construction and operation ofdetonator 10 are similar to prior art devices and therefore such neednot be discussed in detail.

[0039] In accordance with the present invention, shell 12 is of constantdiameter and has along its entire length a shelllength-to-outside-diameter ratio much greater than that of prior artdetonators. Typical of the detonators of the present invention, theshell 12 and the output charge 18 are configured so that output charge18 has a high charge L:D ratio which is much greater than that of priorart constant-diameter detonators. In detonators according to the presentinvention, the charge L:D ratio is at least several times larger thanthat of such prior art detonators. For example, the charge L:D ratio maybe about 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 12:1,20:1, 24:1, orany value between about 3:1 and about 24:1. In a particular embodiment,the charge L:D ratio is about 8.7:1. When a detonator is configured asdescribed herein, it is possible to dispose a plurality of acceptorlines along the side of the detonator, all of which overlay the outputcharge, thereby achieving reliable signal transfer to each of them.

[0040] Generally, the dimensions and ratios of length to (outside)diameter of the shell 12 and of length-to-diameter ratio of theexplosive output charge 18 as described above, apply as well to theother illustrated embodiments of the present invention.

[0041]FIG. 3 shows detonator 10 with one array of shock tubes 24disposed transversely of the longitudinal axis thereof with all eight ofthe receptor lines, comprised in the illustrated embodiment of shocktubes 24, being disposed to be initiated by detonation of explosiveoutput charge 18.

[0042]FIG. 3A is a cross-sectional view taken along line I-I of FIG. 3,and shows that, optionally, shock tubes 24 may be pressed intoconforming contact with shell 12 of detonator 10 in the area ofexplosive charge 18. By “conforming contact” it is meant that shocktubes 24 are forced against shell 12 so that they make more thantangential contact therewith. A suitably designed connector block of thetype illustrated in FIGS. 5 and 5A may be utilized for the purpose. Inmany cases, simple tangential contact will suffice.

[0043]FIG. 4 shows another embodiment of the present inventioncomprising a detonator 110 which is substantially identical to thatdescribed in detail with respect to FIGS. 2 and 3, except that it lacksthe equivalent of pyrotechnic delay train member 20 of the embodiment ofFIGS. 2 and 3. Thus, detonator 110 is an instant-acting detonator and iscomprised of a shell 112 having a closed end 112 a, an open end 112 b,and a crimp 112 c which secures to detonator 110 a shock tube 114 whichterminates in an end 114 a which abuts an isolation member 116. Twoarrays of eight receptor lines each comprising, in the illustratedembodiment, shock tubes 24, are disposed along the length of explosiveoutput charge 118 for initiation by detonation of explosive outputcharge 118. It is seen that the number of receptor lines which can beinitiated by a single detonator is increased as compared to prior artconstant diameter detonators wherein at most only 6 or 8 receptor linescould be clustered about the explosive tip of a conventional detonator.Shock tubes 24 extend transversely of the longitudinal axis of detonator110; in the illustrated embodiment, they are disposed perpendicularlythereto.

[0044] Referring now to FIGS. 5 and 5A, a connector block 26 has atube-retaining member 28 affixed to one end of a body portion 30. Asseen in FIG. 5A, body portion 30 has an enlarged head 36 and an enlargedtail 37. Body portion 30 also has a channel 30 a extending therethroughand in which a detonator, e.g., detonator 10 of FIGS. 2 and 3, isreceived. Detonator 10, as described above, is provided with anon-electric signal transmission line comprising, in the illustratedembodiment, shock tube 14. As is well known in the art, a retainer 38 isformed within the portion of channel 30 a contained within tail 37 inorder to prevent withdrawal of detonator 10 from connector block 26.Tube-retaining member 28, as seen in FIG. 5A, has a pair of paralleltube-retaining slots 28 a, 28 b formed therein within which are receivedrespective arrays of shock tubes 24, disposed perpendicularly to thelongitudinal axis of detonator 10. A pair of tube entry slots 32 a and32 b are formed to permit insertion of shock tubes 24 into,respectively, tube-retaining slots 28 a and 28 b. Protrusions 34 a, 34 bare formed on the sloped portions of head 36 within tube entry slots 32a and 32 b. Protrusions 34 a, 34 b narrow the openings intotube-retaining slots 28 a and 28 b provided by tube entry slots 32 a and32 b so that shock tubes 24 are temporarily slightly deformed as theyare forced past protrusions 34 a and 34 b. The latter thereafter serveto prevent shock tubes 24 from being pulled out of tube-retaining slots28 a, 28 b when tensile stresses are imposed on shock tubes 24 duringpreparation of a blast set-up, or otherwise.

[0045] For reasons of safety and economy, it is generally preferred,especially in surface applications, to employ detonators containing nomore than the amount of explosive output charge material that is neededfor reliable signal transfer. Conceivably, an explosive output chargehaving a charge L:D ratio in accordance with the present invention couldbe attained simply by filling a conventional detonator shell with alarger explosive output charge. That would not, however, be practicalor, in some cases, possible, for a number of reasons. One is that thelarge quantity of explosive output charge that results would leave aninsufficient length of shell to accommodate other components, such as arelatively long delay train member. As discussed above, the practicallyavailable length of a detonator shell is about 3.1 inches (78.7 mm),often only about 2.5 to about 3 inches (63.5 to 76.2 mm), and so thereis only a limited amount of room within the detonator shell. Anotherreason is that such a quantity of explosive would provide much too largean explosive force for surface connector applications, creating too muchshrapnel being propelled at great force, with concomitant risk ofsevering connected signal transfer lines. One feature of the presentinvention is that it provides a detonator shell configured to provide anexplosive output charge with the desired high charge L:D ratio withoutsubstantially changing the overall output strength of the detonator,e.g., without the use of significant additional quantities of explosivematerial, as compared to prior art constant diameter detonators, andwithout incurring the problems associated with two-diameter detonatorsof the type illustrated in FIG. 1. TABLE I provides the result ofcalculations of the number of standard receptor lines, comprising shocktube having an outer diameter of 0.118 inch (3.00 mm), that can bearranged side-by-side along one side of the output region of a detonatorto overlie explosive output charges of various lengths. TABLE IEmbodiments of the Invention A B C D Prior Art ID of Detonator 0.1 0.10 0.120 0.130 0.260 Inches (mm) (2.54)  (2.54)  (3.05)  (3.30) (6.60)Charge Length 1.0 0.860 0.602 0.514 0.129 Inches (mm) (25.4) (21.84)(15.29) (13.06) (3.28) Charge L:D 10.0:1 8.7:1 5.0:1 4.0:1 0.5:1 Numberof standard 8   7    5    4    1    shock tube receptor linesaccommodated on one side of the detonator for lateral initiation*

[0046] If the dual-array arrangement of FIG. 3 is used, the number ofstandard shock tube receptor lines accommodated as shown in TABLE I, isdoubled.

[0047] According to one embodiment of the present invention identifiedas embodiment C in TABLE I, a detonator shell having an inside diameterof 0.12 inch (3.05 mm) and an outside diameter of 0.15 inch (3.81 mm)contains an explosive output charge of lead azide with a charge lengthof 0.6 inch (15.29 mm). Such a detonator accommodates up to fivestandard receptor lines, which have outer diameters of 0.118 inch (3.00mm) disposed alongside one side of the detonator coextensively with theexplosive output charge in the manner illustrated in FIG. 4. Up to tenstandard receptor lines can be accommodated using the arrangement ofFIG. 3. Five such shock tubes placed side-by-side in abutting contactwill occupy 5 times 3.00 mm or 15.00 mm of the 15.29 mm length of theexplosive output charge.

[0048] Small-diameter detonator shells as exemplified by embodiments Athrough D of TABLE I cost considerably less to make than comparableconventional large-diameter detonator shells, and much less thancomparable variable-diameter shells as shown in the above-described U.S.Pat. No. 6,349,648 and 6,305,287 and illustrated in FIG. 1. A typicaltwo- to three-inch (50.8 to 76.2 mm) length of the shells of embodimentsA through D could easily additionally accommodate other components ofthe detonator, e.g., a delay train member interposed between the end ofan input signal transmission lines, e.g., a shock tube, connected to thedetonator at the open end thereof, and the explosive output charge.

[0049] A pyrotechnic delay train member in the detonators of the presentinvention has a reduced size and cost as compared to a comparableconventional, larger-diameter pyrotechnic delay train. Such pyrotechnicdelay train members comprise a charge of relatively slow-burningpyrotechnic material disposed within a metal tube. Thepyrotechnic-containing tube may be made as a large-diameter tube whichis drawn to reduce its diameter and thereby highly compress itspyrotechnic powder core to thereby reduce variations in burn time of thepyrotechnic, or the pyrotechnic may be pressed into a metal tube ofdesired diameter, or pressed into the detonator shell. Once thepyrotechnic-filled tube is drawn to its desired diameter, it is cut tolength. The use of the small-diameter detonator shells of the presentinvention permits the drawing of the pyrotechnic-filled tube to acorrespondingly small diameter, thereby obtaining a greater length ofdelay train for a given amount of pyrotechnic and metal material ascompared to a larger diameter delay train member. For example, drawing agiven metal-encased pyrotechnic core tube to a diameter of one-eighthinch (3.18 mm) yields from the same starting tube four times the lengthof delay train that would be obtained if the starting tube were drawn toa one-quarter inch (6.35 mm) diameter. The four-fold increase in yieldis attained with no increase in materials cost and with substantiallythe same or only very slightly increased labor and processing costs. Thecost of the delay train members is thus reduced on a per-unit lengthbasis.

[0050] In addition, the detonators of the present invention may functionwith a smaller explosive output charge than prior art constant-diameter(large diameter) detonators, thereby reducing the cost of explosive perdetonator as well as reducing the noise and generation of shrapnel,which is important when the detonator is used in surface applications.

[0051] Another way of increasing the charge L:D ratio with the samequantity of explosive is to use a greater volume of relatively lowdensity explosive, such as PETN, instead of a higher-density explosivein the explosive output charge. For example, lead azide at a density of3.0 g/cc may be replaced with PETN at a density of 1.5 g/cc. For anotherexample, the output charge may comprise 130 milligrams PETN and 40milligrams lead azide, instead of 170 mg lead azide. In one suchembodiment, a shell with an interior diameter (“ID”) of about 0.125 inch(3.18 mm) may hold an output charge comprising a combination of PETN andlead azide with a length of about 0.6 to about 1 inch (15.24 to 25.4mm).

[0052] The lengths of explosive output charges of various overalldensities in detonator shells having the inside diameters (“ID”)indicated in TABLE I are shown in TABLE II. TABLE II Charge heights of190 milligrams of explosive output charge at various Detonator IDs andcharge densities Average Density of Explosive Output Charge (g/cc) 1.7g/cc 1.8 g/cc 1.9 g/cc 2.2 g/cc 3.0 g/cc Inside Diameter Length ofExplosive Output Charge of Detonator Inch (mm) 0.10 inch 0.87 in. 0.82in. 0.78 in. 0.67 in. 0.49 in. (2.54 mm) (22.10) (20.83) (19.81) (17.02)(12.45) 0.12 inch 0.60 in. 0.57 in. 0.54 in. 0.46 in. 0.34 in. (3.05 mm)(15.24) (14.48) (13.72) (11.68)  (8.64) 0.13 inch 0.51 in. 0.48 in. 0.46in. 0.40 in. 0.29 in. (3.30 mm) (12.95) (12.19) (11.68) (10.16)  (7.37)0.260* inch  0.13 in. 0.12 in. 0.11 in. 0.10 in. 0.07 in. (6.60 mm) (3.30)  (3.05)  (2.79)  (2.54)  (1.78)

[0053] As noted above, especially in surface applications, e.g.,applications which utilize a connector block such as that illustrated inFIGS. 5 and 5A, it is sometimes desired to attenuate the explosiveoutput attained by the detonators of the present invention. One approachis simply to dilute the explosive output charge 18 with inert material,for example, to combine a pulverulent inert filler with the explosivepowder, or to utilize a plastic bonded explosive as the explosive outputcharge 18 of the embodiment of FIGS. 2 and 3. Another expedient is shownin FIG. 6, which shows detonator 10 of FIGS. 2 and 3 fitted with anexternal attenuator sleeve 40. Attenuator sleeve 40 may be made from anysuitable material, including aluminum, steel, or a synthetic polymericmaterial (“plastic”). It may be affixed to shell 12 of detonator 10 byany suitable means including a sealant or adhesive interposed betweenthe interior of external attenuator sleeve 40 and the exterior of shell12. In FIG. 6, not all the components are numbered, inasmuch as thecomponents of detonator 10 were previously described in detail.

[0054]FIG. 7 shows another embodiment for attenuating the force of theexplosive output in which a detonator 210 is comprised of a shell 212having a closed end 212 a, an open end 212 b and a crimp 212 c formedabout a bushing 42 which seals open end 212 b about a non-electric inputsignal transmission line comprising, in the illustrated embodiment, ashock tube 214 which terminates in an end 214 a An isolation member 216is interposed between a pyrotechnic delay train member 220 and anexplosive output charge 218 disposed within shell 212 at closed end 212a thereof. An internal attenuator sleeve 44 is positioned within shell212. Internal attenuator sleeve 44 may be made of any suitable material,such as a plastic, and its presence adjacent the closed end 212 a ofshell 212 is seen to reduce the volume of explosive output charge 218,thereby attenuating the blast effect.

[0055]FIG. 8 illustrates yet another embodiment of the invention showinga detonator 310 comprised of a shell 312 having a closed end 312 a, anopen end 312 b, and crimp 312 c which seals open end 312 b about anincoming shock tube 314. As in the case of the embodiment of FIG. 7,isolation member 316 separates end 314 a of shock tube 314 frompyrotechnic delay train member 320 which is disposed in signal transfercommunication with explosive output charge 318 disposed within shell 312at closed end 312 a thereof. In this embodiment, an extended internalattenuator sleeve 46 extends from closed end 312 a to open end 312 b ofshell 312. Extended internal attenuator sleeve 46 is made of anysuitable compressible material, such as a plastic and, by being extendedthrough the area of crimp 312 c, serves as a replacement for the bushing42 of the embodiment of FIG. 7. As is the case with the embodiment ofFIG. 7, the presence of extended internal attenuator sleeve 46 reducesthe volume of the explosive output charge 318.

[0056]FIG. 9 shows yet another embodiment of the present invention, inwhich a detonator 410 comprises a shell 412 having a closed end 412 a,an open end 412 b and a crimp 412 c. Shock tube 414 terminates in an end414 a which faces an isolation member 416 which abuts pyrotechnic delaytrain member 420. In this embodiment, isolation member 416 extends toopen end 412 b, and crimp 412 c is formed about isolation member 416,which thus serves both as an isolation member and a replacement for theseparate bushing 42 of the embodiment of FIG. 7. Explosive output charge418 is disposed at the closed end 412 a of shell 412.

[0057]FIG. 10 shows detonator 410 of FIG. 9 equipped with an extendedexternal attenuator sleeve 48 which extends from closed end 412 a toopen end 412 b. As compared to the short attenuator sleeve embodiment ofFIG. 6, the FIG. 10 embodiment avoids a step-down in the outsidediameter of the attenuator-equipped detonator. In FIG. 10, not all ofthe components are numbered, inasmuch as the components of detonator 410were previously described in detail.

[0058] While the invention has been described herein with reference toparticular embodiments thereof, it will be understood by one of ordinaryskill in the art that numerous variations to the described embodimentswill fall within the spirit of the invention and the scope of theappended claims.

What is claimed is:
 1. A non-electric detonator comprising: acylindrical shell defining a shell interior, the shell having asubstantially constant outside diameter not greater than about 6 mm, aclosed end and an opposite, open end; an explosive output chargecontained within the shell at the closed end thereof, the explosiveoutput charge being in the shape of a cylindrical column and having acharge L:D ratio of from about 3 to about 24; and a non-electric inputsignal transmission line received and sealed within the open end of theshell and disposed in signal-transfer relationship with the explosivecharge.
 2. A non-electric detonator comprising: a cylindrical shelldefining a shell interior and having a length as defined below, theshell being of substantially constant outside diameter not greater thanabout 6 mm, and having a closed end and an opposite, open end; anexplosive output charge contained within the shell at the closed endthereof; a non-electric input signal transmission line received andsealed within the open end of the shell and disposed in signal-transferrelationship with the explosive charge; and the length of the shellbeing such that the ratio of its length to its diameter is from about 8to about
 23. 3. The detonator of claim 1 or claim 2 wherein the shellhas an outside diameter of from about 3.0 to about 5.5 mm.
 4. Thedetonator of claim 3 wherein the length of the shell is from about 25 toabout 79 mm.
 5. The detonator of claim 1 or claim 2 wherein the lengthof the shell is from about 25 to about 79 mm.
 6. The detonator of claim1 or claim 2 wherein the explosive output charge is in the shape of acylindrical column having a charge length-to-diameter ratio of fromabout 4 to about
 10. 7. The detonator of claim 1 or claim 2 wherein theexplosive output charge is in the shape of a cylindrical column having alength of from about 20 to about 26 mm.
 8. The detonator of claim 7wherein the explosive output charge has a diameter of from about 2.5 toabout 5 mm.
 9. The detonator of claim 1 or claim 2 wherein the inputsignal transmission line comprises shock tube.
 10. The detonator ofclaim 1 or claim 2 further comprising a delay train member interposedbetween, and in signal-transfer relationship with, the explosive outputcharge and the input signal transmission line.
 11. The detonator ofclaim 1 or claim 2 wherein the explosive output charge contains an inertdiluent.
 12. The detonator of claim 11 wherein the explosive outputcharge is substantially in the shape of a cylindrical column having acharge length-to-diameter ratio of from about 4 to
 10. 13. The detonatorof claim 11 wherein the explosive output charge has a length of about 20to about 26 mm and a diameter of from about 2.5 to about 5 mm.
 14. Thedetonator of claim 1 or claim 2 wherein the explosive output charge isin the shape of a cylindrical column and an attenuation sleeve isdisposed about at least a portion of the length of the explosive charge.15. The detonator of claim 14 wherein the attenuation sleeve is disposedwithin the shell.
 16. The detonator of claim 14 wherein the attenuationsleeve is disposed on the exterior of the shell.
 17. The detonator ofclaim 14 wherein the attenuation sleeve extends over the entire lengthof the explosive charge.
 18. The detonator of claim 17 wherein theexplosive output charge is in the shape of a cylindrical column having acharge length-to-diameter ratio of from about 4 to
 10. 19. The detonatorof claim 17 wherein the explosive output charge has a length of about 20to about 26 mm and a diameter of from about 2.5 to about 5 mm.
 20. Thedetonator of claim 1 or claim 2 wherein the shell has an inside diameterand the input-signal transmission line has an outside diameter which issubstantially the same as the inside diameter of the shell.
 21. Thedetonator of claim 20 wherein the shell has an inside wall and thedetonator further comprises a sealant disposed between the input signaltransmission line and the inside wall of the shell and disposed to sealthe shell interior from the environment.
 22. A non-electric detonatorcomprising: a cylindrical shell defining a shell interior and having aclosed end and an opposite, open end, the shell being of substantiallyconstant outside diameter not greater than about 6 mm, and ofsubstantially constant inside diameter; an explosive output chargecontained within the shell at the closed end thereof, the explosiveoutput charge having the shape of a cylindrical column having a lengthof from about 10 to about 26 mm and a diameter of from about 2.5 toabout 5 mm; and a non-electric input signal transmission line receivedand sealed within the open end of the shell and terminating in an enddisposed within the shell in signal-transfer relationship with theexplosive charge.
 23. The detonator of claim 22 further comprising adelay train interposed between, and in signal-transfer relationshipwith, the explosive charge and the input signal transmission line. 24.The detonator of claim 22 wherein the input signal transmission linecomprises shock tube.
 25. The detonator of claim 22 or claim 24 whereinthe inside diameter of the shell is approximately equal to the outsidediameter of the input signal transmission line and the shell is crimpedonto the input signal transmission line.
 26. The detonator of claim 25wherein a sealant is interposed between the shell interior and the inputsignal transmission line at the location at which the shell is crimpedto thereby seal the shell interior from the environment.